Bald John jet stack questions

TebKLR · Post by **TebKLR** » Sat Aug 11, 2012 11:27 pm

All - 2008 Stella 2T
Running a non-catalyzed PX 125 exhaust
deblued air filter

Installed the Bald John jet stack with a 100 main.

The thing runs GREAT when tipping into the throttle, but not so hot at mid range partial throttle openings....."seems" like it may be overly rich.

Any similar experiences you'd care to share? Did you come up with a sure-fire solution?

Thanks, Tom

double-o-soul · Post by **double-o-soul** » Sat Aug 11, 2012 11:42 pm

any particular reason for the exhaust?
is the air filter a p200 filter or otherwise drilled above the jets?
whats the mix screw set at?
what altitude are you at?
do you still have the 98 main? try that one?

TebKLR · Post by **TebKLR** » Sun Aug 12, 2012 1:44 pm

The exhaust was recommended in lieu of a Sito (less costly, no cat, quiet, etc)

Air filter is Stella but de-blued. No holes drilled in it.

Elevation is approx 485'

Idle screw is 3/4 turn out.

As I mentioned, scoot runs great when tipping into the throttle. Main is 100 and seems just right. Idles fine.

It's the mid-range partial throttle stuff that's rough. Different mixer?

double-o-soul · Post by **double-o-soul** » Sun Aug 12, 2012 5:13 pm

do you know how to do a plug chop?
http://modernvespa.com/forum/topic52333

TebKLR · Post by **TebKLR** » Sun Aug 12, 2012 8:41 pm

Yes I do know how to do that....

Thank you!

Lokky · Post by **Lokky** » Sun Aug 12, 2012 9:00 pm

from what I understand the sito is simply a replica of the pre-catalyzed stock exhaust.

Bcon · Post by **Bcon** » Mon Aug 13, 2012 12:22 am

I've found mine to be slightly rich in the mid-range with the BJ stack. I tried one leaner on the low speed jet, but it ran worse so I went back to the recommendation.

Did you replace the mixer tube also? The stock one never seemed to work right. You can try a different mixer than the BJ recommendation, it's just trial and error to find what runs right.

Mine's not perfect, but it's certainly way better than the stock jetting (I run a P200 air filter and a Sito Plus, otherwise stock). Mine's running with the BJ recommendation and a 105 main right now.

double-o-soul · Post by **double-o-soul** » Mon Aug 13, 2012 5:40 pm

Bcon...
we're essentially the same altitude and same setup, I have GGR hot reeds installed though and I still only run 100 main, and it's perfect, maybe even a tiny bit rich.
105 seems crazy rich for our setup. have you done plug chops? mines always a nice chocolaty brown.

oh the one difference may be that i have a deblued and drilled air filter whereas you have the actual p200 filter.... i was told however, that the mods I did make it essentially a p200 filter.

double-o-soul · Post by **double-o-soul** » Mon Aug 13, 2012 5:49 pm

to the OP:
idle screw is NOT the mix screw. the mix screw is at the bottom back end of your carb. sticks out through the airbox and is sometimes covered by a grommet. not that it should matter too much, but setting this can often compensate for any tiny jetting incompatibilities. this mix screw should be around 2 and a half turns out to start.

If you are indeed running rich, try drilling holes into the air filter in the heart shaped section above the jets. you can search the scootercentral.net forums for pictures and specs. that should give you some more airflow.

another poster asked about your mixtube which is an important part of the bald john setup. go up to AT LEAST a BE3. mixtubes can be a bit confusing label wise, not as simple as mains:
http://www.lmlocgb.co.uk/phpBB3/viewtopic.php?t=1707

Bcon · Post by **Bcon** » Tue Aug 14, 2012 1:47 pm

double-o-soul wrote:Bcon...
we're essentially the same altitude and same setup, I have GGR hot reeds installed though and I still only run 100 main, and it's perfect, maybe even a tiny bit rich.
105 seems crazy rich for our setup. have you done plug chops? mines always a nice chocolaty brown.

oh the one difference may be that i have a deblued and drilled air filter whereas you have the actual p200 filter.... i was told however, that the mods I did make it essentially a p200 filter.

Mine's rich in hot weather with a 105 main. I tuned it (plug chops) in the spring when it was in the 40's, and I haven't changed it. (sorry to admit that I don't care for riding when it's in the 90's+ and humid, which has been all summer here!). It was slightly on the rich side then, but acceptable.

My P200 wire mesh filter doesn't have the holes drilled above the jets. I think it was the T5 filters that had that "feature".

JohnKiniston · Post by **JohnKiniston** » Tue Aug 14, 2012 6:10 pm

Bald John may still check his account over on StellaSpeed, You could try PMing him if your really stumped.

I've never drilled holes in my filters, I just use the p200 filters as is.

You did change your E3 for a BE3 correct?

If your local shop has one you could try switching out the BE3 for a BE4 and see if it helps but do a couple plug chops to make sure you dont go lean with it.

viney266 · Post by **viney266** » Wed Aug 15, 2012 1:16 am

I'll go PM him now

Back before I had the DR I ran a 103 Main with a BJ set-up on a SIP road,GGR reeds and a P200 filter. Ran great, every once in a while I would get a little blubber in the mid range, but it alvays went away with just a touch more throttle. This isn't fuel injection, it will never be quite perfect. SOOOOO much better than the stock set-up genuine was forced to install.

az_slynch · Post by **az_slynch** » Tue Sep 18, 2012 4:20 pm

viney266 wrote:I'll go PM him now

Back before I had the DR I ran a 103 Main with a BJ set-up on a SIP road,GGR reeds and a P200 filter. Ran great, every once in a while I would get a little blubber in the mid range, but it alvays went away with just a touch more throttle. This isn't fuel injection, it will never be quite perfect. SOOOOO much better than the stock set-up genuine was forced to install.

The trick I've found for quashing the mid-throttle blubbering is to swap out the stock throttle slide with a Dellorto #3 slide. These came in the SI 20.20D carbs fitted to Rally 180s. It has a cutout in the bottom of the slide that allows a bit more air in through the slide chamber (heck, there's an air inlet through the filter for a reason) and works in the 1/3-1/2 throttle range.

http://www.sip-scootershop.com/en/produ ... +_68230300

If you don't want to buy a new slide, the cutout section is 17.5mm long, 8mm wide and 1.92mm deep. It started about 3mm away from the notch on the venturi end of the slide. Could probably be replicated with a vice, a Dremel and a steady hand.

fisher1 · Post by **fisher1** » Tue Sep 18, 2012 8:26 pm

All - 2008 Stella 2T
Running a non-catalyzed PX 125 exhaust
deblued air filter

Installed the Bald John jet stack with a 100 main.

The thing runs GREAT when tipping into the throttle, but not so hot at mid range partial throttle openings....."seems" like it may be overly rich.

Any similar experiences you'd care to share? Did you come up with a sure-fire solution?

I'm at a similar altitude with the same type exhaust ("big pipe" replacement PX 125/150 exhaust) & filter. My '09 2T requires jets much richer than the Bald John starting points based on CHT temperature reading, plug chops and general performance.

During the hottest point in summer. I found that a 104 or 105 Main and 52/140 Idle jets were needed to retain the stock cylinder head temperatures as well as a light chocolate plug.

That resolved the fuel/air mix, but that's a lot more fuel than the leaner stock jets pass, which means the automixer's oil/fuel ratio is reduced. So, I add 1oz of 2T oil to every 2 gal of gas (about .3%) to restore the mix back to the recommended 2.0%.

I wouldn't do any changes without a CHT guage to monitor, and I'd retorque the exhaust clamp after a few hundred miles to ensure there's no air leak at the exhaust joint which (believe it or not) will seriously increase the cylinder temp.

fisher1 · Post by **fisher1** » Tue Sep 18, 2012 8:42 pm

During the hottest point in summer. I found that a 104 or 105 Main and 52/140 Idle jets were needed to retain the stock cylinder head temperatures as well as a light chocolate plug.

I should also add ....... before someone comments that the cooler weather will cool the engine and thus reduce the need for a 104 or 105 - or richer Idle jet.

The upcoming cooler weather means denser air which creates a leaner mix. The piston - cylinder head heat from this leaner mix due to cool-dense air will more than compensate for the cooler air flow over the fins.

Baldjohn · Post by **Baldjohn** » Tue Sep 18, 2012 9:31 pm

TebKLR wrote: 100 main

The 100 main jet is for the cat pipe. Any other pipe is going to be at least 5 jet points higher.

Slap a 105 in. Warm it up and readjust your idle fuel screw on the back of your carb.

http://myscooterwontstart.com now has a link for your forum : )

Nice to see you guys have a Stella section.

http://www.226vintage.com/docs/ProjectStella.pdf

double-o-soul · Post by **double-o-soul** » Wed Sep 19, 2012 2:36 am

i'm on a 103 close to sea level with a sito+

john, do you think a 105 is still in order even for a sito+?

thanks in advance,
Randy

Baldjohn · Post by **Baldjohn** » Wed Sep 19, 2012 11:17 am

double-o-soul wrote:i'm on a 103 close to sea level with a sito+

john, do you think a 105 is still in order even for a sito+?

thanks in advance,
Randy

A 105 at least! No smaller. If you do a lot of wide open throttle riding, try a 110 or 115.

Bcon · Post by **Bcon** » Wed Sep 19, 2012 5:38 pm

Baldjohn wrote:
TebKLR wrote: 100 main
The 100 main jet is for the cat pipe. Any other pipe is going to be at least 5 jet points higher.

Slap a 105 in. Warm it up and readjust your idle fuel screw on the back of your carb.

http://myscooterwontstart.com now has a link for your forum : )

Nice to see you guys have a Stella section.

http://www.226vintage.com/docs/ProjectStella.pdf

Thanks for popping in Bald John!

I certainly appreciate your jetting starting point recommendations, saved me a lot of trial and error!

Modern Buddy

Bald John jet stack questions

Bald John jet stack questions

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Re: Bald John jet stack questions

Re: Bald John jet stack questions